全文获取类型
收费全文 | 366篇 |
免费 | 25篇 |
国内免费 | 38篇 |
专业分类
化学 | 292篇 |
晶体学 | 6篇 |
力学 | 26篇 |
综合类 | 4篇 |
数学 | 13篇 |
物理学 | 88篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 8篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 30篇 |
2012年 | 38篇 |
2011年 | 31篇 |
2010年 | 23篇 |
2009年 | 23篇 |
2008年 | 17篇 |
2007年 | 15篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 6篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有429条查询结果,搜索用时 356 毫秒
81.
合成了两种单体-双酚A二炔丙基醚与4,4'-联苯二苄叠氮,研究了一种新的低温聚合体系--双酚A二炔丙基醚与4,4'-联苯二苄叠氮在烘箱中的本体聚合行为.通过红外、核磁共振以及质谱、元素分析等表征了单体的结构.利用傅立叶红外技术(FT-IR)跟踪了聚合反应过程中特征基团的变化,采用差示扫描量热技术(DSC)研究了聚合反应工艺及其动力学,热失重分析(TGA)考察了聚合产物的热稳定性能.通过Kissinger法和Ozawa法获得了反应的一些动力学参数.结果表明,双酚A二炔丙基醚与4,4'-联苯二苄叠氮易发生1,3-偶极环加成聚合反应,在聚合物结构中形成三唑五元环,它们的聚合起始温度在70℃左右,聚合反应的主反应是一级反应,表观活化能△E=84.6kJ/mol,指前因子A=4.865×1010min-1.同时发现,聚合物具有较好的热稳定性能. 相似文献
82.
傅里叶变换用于铁和锌的同时光度测定 总被引:7,自引:0,他引:7
研究了傅里叶变换技术用于铁锌二组分的同时分光光度测定,采用傅里叶变换对吸光度数据进行预处理,再结合目标转换因子分析或偏最小二乘分析,结果较普通的目标转换因子分析或偏最小二乘法有显著改善。以傅里叶变换-偏最小二乘法就用于实际铝合金样品中铁和锌的同时测定,结果令人满意。 相似文献
83.
84.
85.
Fei Geng Quan Cao Zhen Li Liqiang Zheng Jianhong Xiao 《Journal of Dispersion Science and Technology》2013,34(1):92-99
Aqueous solutions of mixed cationic and anionic surfactants, cetyltrimethylammonium bromide (CTAB) and sodium laurate (SL), have been studied by steady-state rheology and dynamic oscillatory technique. Wormlike micelles can form due to attractive interactions between the oppositely charged headgroups of CTAB and SL. The wormlike micelles formed by CTAB/SL have been compared with that of cetylpyridinium bromide (CPB)/SL by steady-state rheology method. Effects of additional components such as NaBr, 1-propanol, 1-butanol, polyvinylpyrrolidone (PVP) on the micelles formation process have also been investigated. Cole-Cole plot has been applied to study the dynamic viscoelasticity of the wormlike micelles. 相似文献
86.
87.
Jianhai Mu Ganzuo Li∗ Zhengwu Wang Liqiang Zheng 《Journal of Dispersion Science and Technology》2013,34(7):999-1005
The changes of cloud points and surface tensions of a nonionic surfactant dodecyl polyoxycthylene(5) polyoxypropylene(4) ether (LS54) in aqueous solutions with added polyvinylpyrrolide (PVP-K90) were determined in order to evaluate polymer-surfactant interactions in the bulk solutions. A new model, corona-shaped intra-chain micelles, was applied lo these phenomena and the thermodynamic parameters of micellization were determined. 相似文献
88.
We consider an M/PH/1 queue with workload-dependent balking. An arriving customer joins the queue and stays until served if and only if the system
workload is no more than a fixed level at the time of his arrival. We begin by considering a fluid model where the buffer
content changes at a rate determined by an external stochastic process with finite state space. We derive systems of first-order
linear differential equations for the mean and LST (Laplace-Stieltjes Transform) of the busy period in this model and solve
them explicitly. We obtain the mean and LST of the busy period in the M/PH/1 queue with workload-dependent balking as a special limiting case of this fluid model. We illustrate the results with numerical
examples.
相似文献
89.
Junkun Tang Liqiang Wan Yan Zhou Lvyuan Ye Xiaohui Zhou Farong Huang 《Journal of Solid State Electrochemistry》2017,21(3):725-734
Sulfonated polytriazole (SPTA) proton exchange membranes (PEMs) with a series of sulfonation degrees was synthesized based on click chemistry from a rigid diazide monomer, 4,4′-bis(azidomethyl)-1,1′-biphenyl (BAMB), with 2,2-bis[(4-propargyloxy)phenyl]propane (BPBPA) and 4,4′-diazido-2,2′-stilbenedisulfonic acid disodium salt (DSDA). The structure of the copolymers was characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). As a result of the introduction of rigid biphenyl structure and the ionic interaction between triazole rings and sulfonic acid groups, the SPTA membranes exhibited higher water uptake and lower swelling ratio compared to NRE211 membrane, indicating excellent dimensional stability. AC impedance revealed that the proton conductivity of SPTA membranes ranged from 2.5 to 35 mS/cm at 30 °C and 13–105 mS/cm at 80 °C. Besides, the membranes have high thermal and oxidative stability, good mechanical property, and low methanol permeability as well. 相似文献
90.